Reefkeeping
Made Easy
What Was Not Explained
What Was Not Explained
A
Fact-sheet of the Thread from The Reek Tank Forums
Hosted
by Geoff
Contributions
by: Fat Tony, wharyat, dmora723, chrisd, Elegance Coral, embross67,
Nate_Bro, FutureDoc, et al.
The biggest things we will be discussing in this
document are the biological process that are going on in our systems.
These biological process are what most of the false information that
is out there is about. This includes reef forums and LFS.
The two main elemental processes we will be
discussing are the Nitrogen and Phosphate cycles that are occurring
in our systems. these two elements lead to the greatest confusion
about what is going on in our little slices of ocean.
I am tired of all of the bad info that is out
there. We need to get this hobby under control or it will not make
it much longer with all of the environmental trouble that is going on
around the world. This hobby of ours is actually pretty self
sustaining if we just understand the basics.
Nitrification
The process of ammonia to nitrite and nitrite to
nitrate takes place in oxygenated areas.
Nitrates are a great algae fertilizer.
The greater the flow, the longer detritus remains
suspended to be removed by filtration. This assists in removing the
products that fuel the nitrogen cycle to begin with.
Denitrification
The process of nitrates to N gas takes place in
anoxic areas. The best place for this is live rock.
Sand beds can also process nitrate to N gas, but
live rock is more efficient – substrate is a 2 dimensional surface.
All of the bacteria that handle the entire process
reside very close to each other. With one layer feeding the other.
This is why when the nitrates are free they can not get to the anoxic
layers because they are already feeding on the nitrates that the
layer right next to them are supplying them.
An excess of nitrates means there is an imbalance
between the amount of aerobic areas and anoxic areas.
Phosphates are needed for all life.
They come in two forms – orthophosphates and
inorganic phosphates.
All food contains both types of phosphates.
Phosphates are mined from limestone, or any large
deposits of calcium carbonate. Calcium carbonate is a great
phosphate binder. Live rock, aragonite sand, and coral skeletons are
all composed of calcium carbonate, which means they also contain
phosphates.
Imported organic phosphates break down very
quickly in the SW environment to orthophosphates which are then
immediately taken up by the organisms in the system.
High phosphate levels restrict the calcification
of salt water which prevents healthy growth of corals, inverts and
coralline algae. But phosphates also contribute to alkalinity levels
helping to buffer them higher which in turn helps to buffer pH
causing less stress for fish and other inhabitants.
It's important to understand that systems cannot
be rid of phosphate. There is phosphate available in every healthy
reef tank. Even those low nutrient demanding SPS corals can not grow
or replace tissue without phosphate. The goal isn't to eradicate
phosphate. It's simply to keep the concentrations below levels that
can fuel rapid growing organisms like hair algae.
Orthophosphates
Orthophosphates make a great fertilizer for algae.
It is hard to get any reading when testing for
orthophosphates in a working system. The the cyano/algae/bacteria
all want this and will uptake it immediately, binding all
orthophosphates and providing your phosphate test kit with a “0”.
When you are actually getting a reading it means
that all of the bacteria in your system has bound all of the
orthophosphates it can and now there is some free in the water
column.
Orthophosphates are system limiting - if you have
very little, you will have very little available for algae/cyano
growth.
Algae grows as close to the supply of food as
possible.
Purging Phosphates from Live Rock
Bacteria in the LR are able to break off bound
phosphates that are attached to the calcium carbonate. They then
incorporate it into their bodies and bind it. The more phosphates
the more bacterial bodies. When you get enough bacteria together they
create a fair amount of force. This force pushes the dead bacterium
(bacterial flock) out of the LR where it can then be swept away from
the LR. This bacterial flock is heavier then water so it falls to the
bottom, or if your water flow is strong enough it can get pushed
around until 1) it gets removed by the skimmer or 2) settles
somewhere. either in a hard to reach low flow area or your sump/fuge.
if this is planned then it is all good. If you have more sand in
these areas then not so good. The force that the bacteria exert is
known as Turgor. this makes LR self cleaning when it comes to
phosphates.
Live rock will wick phosphates up from the
substrate if in direct contact with it. To prevent this, use
supports to suspend live rock above the surface of the substrate.
Buildup of Phosphates in Substrate
Bacterial Turgor also happens in the substrate.
But the problem with sand is that it is contained on every side but
the top. so the bacterial flock formed from the LR and the sand just
keeps building up in the sand bed till it just gets full. At the
point the Turgor is pushing the flock up into the water column is
when you are able to get phosphate readings from the test kits.
Phosphates can be kept in control by siphoning the
substrate thoroughly. There is nothing living in your sand bed that
is not already living in your LR. Populations from the LR will
quickly repopulate any empty places in your sand bed.
The greater the flow, the longer detritus remains
suspended to be removed by filtration.
Anoxic (denitrifying) layers can be considered “safer” in Live Rock vs. substrate. These areas in rock can be easily purged as long as nitrates and phosphates are kept to levels that will not overload the rock.
Porous live rock is better from a filtration point
of view. The less dense, the more nooks and crannies in it for
bacterial colonization.
Purchasing dry rock in lieu of fresh live rock is
the safest. Allow nitrosomona and nitrobacter bacteria grow, and the
risk of introducing bad hitch hikers is removed. Then get the
coraline from a fellow reefer, if you want to add that to your
system.
Cured live rock does not contain much of the
unwanted critters nor much in phosphates.
If you do not have access to cured rock, you can
cook live rock by placing it in containers of artificial saltwater
with a power head for flow. As the rock purges itself, bacterial
flock will be evident at the bottom of the container. Swish the rock
(to remove any loose bacterial flock), siphon and replace the water
on a weekly basis as the rock sheds. The rock will be cured when
very little flock is visible at the bottom of the container prior to
the regularly scheduled water change.
Cooking rock does not require light or heat unless
a hitchhiker is to be kept. Nitrifying bacteria will continue to
grow in temperatures ranging from 64 – 100 degrees plus. However
they thrive in the range of 77 – 86 degrees. But keeping the water
at reef temperature (78-80 degrees) will speed up the metabolism of
the bacteria, allowing them to process phosphates in the rock faster.
Fresh live rock with the most growth on it is
generally harvested in areas that tend to be lagoons. Algae likes
high nutrient water, and nutrients settle out in low flow areas, such
as lagoons. Live rock from these areas are already loaded with
phosphates.
Concerning denitrification, there is nothing wrong
with coralline covered rock. It tends to not block the LR as much as
you would think. Also if coralline is able to cover your LR then it
is not full of phosphates. If it were then the phosphates would
actually hinder the growth of coralline algae completely. The
phosphate can hurt in the production of calcium carbonate into the
skeleton when present in large quantities.
In “low-poo” systems, less than 1 lb per
gallon is required for adequate live rock filtration.
Don't ever buy live sand. How can it be live if it is in a bag of water? At that point it's just more phosphates to add to your system.
Jump start your system with a very small piece of
LR from a system you trust. The smaller the better. That allows it
to be scrutinized and ensures there are no unwanted hitchhikers on
it. Even a tiny piece of live rock will contain the bristleworms
and pods that everyone needs in their system.
Not only do new tanks start with the nitrogen cycle, but also the silica and phosphate processes. The latter two processes start at around 2-3 weeks and can continue for months. They are commonly referred to as “the uglies”.
Silica and phosphates are made almost immediately
available to the system due to the mechanical means of setting up an
aquarium. As bits of sand and LR rub against each other they break
off little bits. These little bits allow the silica and phosphates
to become loose in the water column. The more sand/LR the greater
the chance of having more of these available right after the system
is setup.
Silica Processes
The main algae that needs scrapped off the glass
is diatomic. It uses silica in its body structure. In the beginning
of a system, diatomic algae is the only real user of silica. It
quickly is able to ramp up and bloom to use up significant amounts of
the silica, hence the brown algae bloom encountered.
Over time as the tank matures, sponges will start
growing under the LR. These sponges also need the silica and will
quickly start uptaking the silica making it less available to the
diatomic algae.
Soft corals and perhaps LPS also use silicates in
their structure.
Sponges and some coral bind up the silicates long
term – unlike the diatomic algae which reproduce and die fairly
rapidly releasing and uptaking the silicates. Until these binding
organisms take off the diatomic algae bloom will continue.
Phosphate Processes
Cyanobacteria and algae are the first organisms to
process phosphates.
Phosphates do not cycle per se. Rather they
fluctuate. They are bound by living organisms and are released as
those organisms die.
Bacteria is the fastest at being able to uptake
phosphates. Algae is second. In an empty system it is a race
between bacteria and algae to deplete the phosphate in the water
column.
As the phosphates are used up they are deposited
on the substrate in a nice layer. This is where the cyano come in.
They grow where the nutrients are, This is helpful to us because it
gives us something to siphon.
Removing the cyano will remove the phosphates in
its biomass. What we are waiting to happen to finally bring the
"uglies" to an end is for the phosphate laden material to
either be removed or sunk somewhere that is unavailable to the algae
and bacteria.
If macro algae is growing then there is a phosphate problem. The macro algae is just another phosphate sponge. If it is able to find phosphates then the calcium carbonate structures are full and are now leaching the phosphates back into the system fueling the algae. Siphoning the sand bed with every water change will keep the phosphate level under control in the sand bed.
Algae do bind
phosphates, but they are also leaky. And like any other organism they
have biological functions. They have wastes they need to get rid of
also.
Deep Sand Beds (DSBs)
DSB's should be thought of as a nutrient sink or
filter. All filters must be cleaned or eventually replaced.
The layers of bacterial activity will start to
creep higher and higher as the DSB fills with phosphates. When the
DSB is new the bacteria are working everywhere, but as the bed fills
up with detritus the bacteria have to move higher in order to not get
choked out by the detritus. When a bed is deep cleaned it opens the
bed up again and allows the bacteria to function throughout the
entire vertical range of the substrate again.
Substrate Husbandry
Siphon the substrate thoroughly with each water
change. There is nothing living in your sand bed that is not already
living in your LR. Populations from the LR will quickly repopulate
any empty places in your sand bed.
When doing water changes, the biggest sources of
waste need to be gone after, That is the detritus you see on top of
the substrate. The point of water changes is to remove wastes.
There are very little wastes in the water column itself, so just
changing the water does little, but replace trace elements, which of
course are called trace for a reason.
Dead bacteria that contain bound phosphates in
their cell structures are expelled from the LR where the flow is able
to sweep it away from the LR and allows it to settle elsewhere. In
nature it is either in the abyss or in lagoonal areas. We all know
what eventually happens to the phosphates in the abyss (think plate
tectonics). That is how the reef cleans itself. The phosphates just
get dumped someplace else, far enough away so that it is not in the
same water column. A substrate siphon IS our abyss.
When doing water changes the biggest source of
phosphates could be the replacement water itself. This is why it is
recommended that all water going into the tank be RO/DI water. We
add a lot of water to our systems through water changes and top off.
Keeping this source as phosphate free is possible goes a long way to
keeping it under control in the system.
Live Rock Husbandry
Live Rock is self-cleaning provided enough flow is
given to wash detritus from it's surface.
Suspend Live rock above the substrate to avoid
phosphates from wicking up from the sand into the live rock.
With the amount of flow needed to keep live rock
clean, it is suggested to go with CC sand instead of the oolitic sand
that is the norm. It is hard to siphon oolitic substrate without
siphoning it up.
Bacterial Flock and Detritus
Strategic flow should be used to get the detritus
suspended, then forced in the correct direction for removal. Either
towards the overflow or intake of the skimmer (HOB).
Suspended detritus needs do be removed so it degrades as little as possible. The only way to completely remove it from contact with the system water is through the use of a skimmer.
Suspended detritus needs do be removed so it degrades as little as possible. The only way to completely remove it from contact with the system water is through the use of a skimmer.
Water changes and aggressive siphoning of the
substrate will also remove detritus.
Skimmers are the only piece of equipment we reefers have at our disposal that actually removes nutrients from the water column immediately. Every other filter we use traps the detritus and can allow it to rot till we actually remove it manually. This includes reactors, filters, and sand.
A trick to make your skimmer even more efficient
is to plumb a UV clarifier immediately before the skimmer. This way
anything that the UV killed or broke down would be taken out by the
skimmer and not allowed to rot elsewhere in the system.
All organisms need down time to actually grow and prosper. Therefore it is not recommended to leave the lights on 24/7.
The zoax (browns and greens) in the corals are
responsible for the photosynthesis and food production along with the
formation of the coral skeleton as a by product of the
photosynthesis.
The other colors we see are from proteins the
coral produces to block light getting to the zoax to keep the zoax
from producing to much oxygen and poisoning the corals.
An overproduction of zoax (browns and greens) in
corals are caused by excess nutrients in the water. Zoax
(photosynthetic algae) feed on phosphates and nitrates.
Higher temperatures cause higher metabolic rates.
Zoax can cause O2 poisoning in coral. The coral will then reduce
zoax levels by expulsion. The result is a bleached coral.
Too much light can also cause zoax to O2 poison
it's host coral, causing bleaching.
Most of the fish we like to keep fall into the planktonivore category. They feed over the entire day whenever food becomes available. The greatest number of reef safe fish will fall into this category. There are also several species of some non-reef safe fish that can be kept in a reef just fine because they are planktonivores. Genicanthus angels, Hemitaurichthys butterflyfish, and Xanthichthys triggerfish are examples. Several of these fish have been difficult to keep because of the fact that we have been told to keep feeding down in order to keep the nutrients down, which is very important. But what happens if you do not have to worry about keeping nutrients down because you are easily able to remove all detritus? When a BB system is run, one can easily see the detrital build up and are able to control the amount of phosphates in the system. This works with whatever biotope you are trying to do, whether it is a lagoon or a reef top. Being able to keep track of the detritus puts you in charge and not the sand. You are no longer reacting to the bacterial flux going on in the sand bed. With good flow all around the LR then it will remain relatively constant in its phosphate purging.
it is important when
feeding to make sure the food is low in orthophosphates. Find a
brand that does not have any preservatives listed on their food
labels.
Blender mush is another
very good type of food - lightly blended so as to produce the
greatest difference in sizes of bits. You want everything from coral
eating size to fish eating size. Everybody has their own size food
they would prefer. This is especially true of corals and some
echinoderms.
All SW critter
purchases should be researched before hand. Some have a very
specific diet that may not be able to be provided for.
During the initial
setup period of a tank with all the free organics, you could also see
population blooms of other organisms that feed off the organisms that
feed off the free phosphates. The most common of these being pods.
There will be a large population of pods that will spike about the 6
month mark when a system is just setup. This population will
ultimately crash by the 1 year mark and will settle out. It is very
tempting to think you can support a pod eating fish when you see all
of these pods, but that is a very short term bloom. This is why it is
recommended to wait at least a year before determining if the pod
population is large enough to support a predator.
Vodka
Carbon dosing (vodka, vinegar, white sugar) is
utilized to reduce nitrates and phosphates and generally adds clarity
to the water. However a skimmer is a necessity with this method.
Carbon dosing works by causing an increase in
bacteria. That bacteria fill the water column up-taking nitrates and
phosphates. The skimmer then removes the bacteria, along with their
bound nitrate and phosphate and exports it from the system.
Carbon dosing will allow increased feeding
schedule due to the lower nutrients. Note that good husbandry will
also allow the same without the dosing.
Carbon dosing also allows the environment to be
pushed more toward an ultra-low nutrient system more suitable for SPS
coral.
By introducing more carbon in the water column, it
allows bacterial to out-compete algae for nitrates and phosphates. Be
warned – an increase in bacterial load can deplete oxygen in the
system causing the higher organisms stress or death.
Increased coloration in corals have been reported
due to feeding on the increase in bacteria in the water column.
Corals have also been reported to pale over time.
Kalkwasser (Lime water)
Kalk, lime water, or pickling lime can be used as
an economical means of calcium supplementation and results in the
raising of pH levels.
It can also reduce levels of magnesium and
phosphate indirectly.
It is normally dosed through top-off water.
Dmora723 here. I'm so glad to see this. Great job.
ReplyDeleteSpecial thanks to Geoff.